In general, you should water your tree when the top of the soil is dry. Each tree uses water at a different rate, so do not water all your trees at once, unless they truly need it. Use a watering can or hose attachment that will cast a soft, rain-like spray so that you do not blast the soil out of the pot.
Pines and junipers go in full sun, while deciduous trees, such as maples and elms, will do well in a spot that gets some shade from late afternoon sun. Indoor, or tropical, trees will want quite a bit of sun. They are used to bright, humid climates found near the equator. If the Summers where you live are hot and arid, you must be careful that your trees do not dry out. You will want to give all your trees dappled sun during Summer. Azaleas will do well in a spot that gets bright sun until noon, with plenty of humidity. Last, it is a good idea to set your trees on a low bench about two feet off the ground. This will keep many of the bugs out of the pot and keep the tree from accidentally being kicked or stepped on. Plus, it looks nice.
A bonsai is not, in many cases, simply a dwarf form of a tree. A bonsai has been dwarfed by training. Training involves pruning, wiring, watering, repotting, fertilizing, etc. As you progress in learning about your tree, you will gradually become more aware of all the aspects of training and their use. For now, trim away any branches and leaves that do not add to the tree you are trying to produce. In order to do this, you must have a good idea of what it is you are trying to do. Take a picture (or draw one) of your tree before you begin work and draw a second, this time of how you want the tree to look in the future. You may or may not keep to this design, but it is important nonetheless to have an idea of the direction you want to take.
Good outdoor (temperate climate) trees for beginners include Green Mound juniper, Trident maple and Chinese elm. These are very forgiving trees, and can adapt to most environments, with proper care. Good indoor (tropical climate) varieties include Ficus and Schefflera. These grow well in lower light conditions found in many homes. They still need as much light as you can supply, however.
Some people mistakenly believe that all bonsai can be kept indoors indefinitely. This is not surprising because these trees are often displayed indoors. However, all bonsai trees are species that grow outside in their native lands and therefore do best when grown outside in fresh air and natural light. That said, some bonsai originate in tropical environments; they do not thrive in cold weather. These trees are classified as “indoor” bonsai because they need to be protected from the cold. Indoor bonsai grow best when kept inside during cold months and outdoors during warm seasons. (See individual tree info for specifics.) We recommend keeping all bonsai, including those grouped as indoor, outside when temperatures are moderate. Most bonsai are temperate climate trees and just like their non-dwarfed cousins in your yard, they need to experience seasonal changes. Winter’s cold, gradually warming spring temperatures, summer’s heat and fall’s progressive cooling drive the normal active growth and dormant rest periods for these trees. While temperate climate trees may be displayed indoors during any season, it is ideal to do this for only a few days at a time. Then move them back outside.
Indoor bonsai are tropical species that must be keep inside when the weather outside is cold. During their months indoors these trees require locations with good light; see specific species care info for details to help choose an ideal site. Indoor bonsai trees also appreciate locations away from drafts and excess heat, i.e. exterior doors and hot air registers. Forced air, hot in the winter and cool in the summer, creates a desert-like environment in most homes. Indoor bonsai, and most other plants, appreciate more moisture. This is easy to achieve with humidity trays, low trays that contain a small amount of water and decorative rocks. Place your bonsai on the rocks in the tray and water from above. The excess water collects in the tray and evaporates to moisten the air. (This humidity is good for people, too!) See Shopping>Supplies & Accessories for tray options. Most outdoor bonsai can, and should, be kept outside year round. Low temperatures are best managed by first choosing a tree that is well suited to your regional weather (see info provided with individual trees) and then providing conditions for successful winter dormancy. In warm parts of the country, no special care is required. In cold areas, winter care for potted bonsai includes two considerations: temperature swings and temperature lows. If winter temperatures in your area drop to 20 degrees the main goal for winter care is to mitigate temperature swings so a few warm days don’t prematurely signal to your tree that spring has arrived and it’s time to start growing. To manage these variations, place your bonsai next to a wall that will shield it from drying winds and mound pine needles or bark mulch around the pot. Create a layer about 3” deep; this will help keep the air temperature around the root ball constant. Check the mulch periodically to confirm that it hasn’t shifted or blown away. Water your bonsai every week or two and never let your tree freeze when dry. Remove the mulch and reposition your tree when reliably warmer spring weather returns. For regions where the weather is very cold move your tree to a location where temperatures stay above 15 degrees – an unheated garage, shed or breezeway is ideal. Sunlight is not necessary as the tree is dormant and isn’t photosynthesizing (turning sunlight into energy) during the winter. Water every week or two and never let your bonsai freeze when dry. Move your tree back to its summer location when reliably warmer spring weather returns.